---

yaml
---
r: 157315
b: refs/heads/master
c: 967cc53
h: refs/heads/master
i:
  157313: 0636083
  157311: a73562f
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5bb459bb45d1ad3c177485dcf0af01580aa31125
+refs/heads/master: 967cc5371113f9806b39a2ebb2174af2883d96fe

trunk/lib/is_single_threaded.c

@@ -22,16 +22,13 @@ bool current_is_single_threaded(void)
 	struct task_struct *p, *t;
 	bool ret;
 
-	might_sleep();
-
 	if (atomic_read(&task->signal->live) != 1)
 		return false;
 
 	if (atomic_read(&mm->mm_users) == 1)
 		return true;
 
 	ret = false;
-	down_write(&mm->mmap_sem);
 	rcu_read_lock();
 	for_each_process(p) {
 		if (unlikely(p->flags & PF_KTHREAD))
@@ -45,12 +42,17 @@ bool current_is_single_threaded(void)
 				goto found;
 			if (likely(t->mm))
 				break;
+			/*
+			 * t->mm == NULL. Make sure next_thread/next_task
+			 * will see other CLONE_VM tasks which might be
+			 * forked before exiting.
+			 */
+			smp_rmb();
 		} while_each_thread(p, t);
 	}
 	ret = true;
 found:
 	rcu_read_unlock();
-	up_write(&mm->mmap_sem);
 
 	return ret;
 }